Lettuce (Lactuca sativa L.) is one of the main leafy vegetables in the world, being present in several countries. Due to its composition, which includes a substance with antioxidant action and beneficial effects on health, it is consumed constantly. However, due to ongoing climate change that has had global effects, the crop has been suffering a reduction in productivity and quality. Thus, technologies aiming to mitigate the effects of climate extremes have been developed. In lettuce production, biostimulants make it possible to improve the growth and sustainable development of plants. This is due to their ability to activate physiological and biochemical processes in plants, resulting in an increase in the production of bioactive compounds such as vitamins, amino acids, and antioxidants. In addition, biostimulants contribute to improving the nutritional quality of lettuces, making them more resistant and adapted to different environmental conditions, resulting in a more sustainable development for the crop. This review aims to compile and discuss the available scientific evidence on the use of biostimulants in lettuce cultivation, addressing their mechanisms of action, the types of substances used, the results obtained in different cultivation systems, and their potential to promote more efficient and adaptable agriculture in the face of environmental changes.

Soil salinization is one of the main factors limiting agricultural productivity, negatively affecting seed germination and initial growth of maize (Zea mays L.). As a sustainable alternative, seaweed-based biostimulants, especially extracts of Ascophyllum nodosum, have stood out in mitigating abiotic stresses. This study aimed to evaluate the potential of A. nodosum extract in inducing tolerance to saline stress in maize seeds of the AL Bandeirante cultivar. To this end, three independent bioassays were conducted under controlled conditions: (i) evaluation of five doses of the extract (0; 0.5; 1.0; 1.5 and 2.0 mL L⁻¹); (ii) effects of five osmotic potentials induced by NaCl (0, −0.2, −0.4, −0.6 and −0.8 MPa); and (iii) the interaction between the most efficient doses and salinity levels, comparing the extract to its mineral fraction. Seed germination, percentage of normal and abnormal seedlings, radicle and epicotyl length, and vigor index were measured. The results demonstrated that doses of 1.0 to 2.0 mL L⁻¹ promoted greater bioactivity, with a 7.3% increase in root length compared to the control. Although increased salinity progressively reduced all variables, with severe effects at −0.6 and −0.8 MPa, the treatment with the extract showed superior performance to the mineral fraction, demonstrating a mitigating effect. It is concluded that A. nodosum extract is an effective strategy to attenuate the damage caused by salinity on seed germination and initial seedling growth in maize, especially under moderate stress.

Melatonin (N-acetyl-5-methoxytryptamine) is a regulatory molecule with potential to increase plant tolerance to water stress by modulating stomatal function, redox balance, and photosynthetic efficiency. However, its physiological effects depend on dose, species, and stress intensity, and studies on Coffea canephora under recurrent drought are scarce. This study evaluated the effects of exogenous melatonin (0, 100, 200, 300, and 400 µM) on young plants of conilon coffee genotype 02 (Clone V12) subjected to three consecutive cycles of water deficit and rehydration. The experiment was conducted in a greenhouse using a randomized block design, with evaluations of gas exchange, water potential, and biomass allocation. Melatonin improved physiological recovery after rehydration, particularly at 100 and 300 µM during the second stress cycle, when photosynthesis reached values similar to the irrigated control. The 400 µM treatment maintained root dry mass close to the control under prolonged deficit, suggesting preferential biomass allocation to the root system. Overall, melatonin effects were more pronounced during recovery than stress, indicating a possible priming action. These results highlight the potential of melatonin as a phytoprotective agent in C. canephora, although responses depend on dose and stress cycle.

Water deficit is one of the main limiting factors for crop establishment and productivity, particularly during seed germination and early seedling development. This study aimed to evaluate the biostimulant potential of Ascophyllum nodosum extract applied to maize (Zea mays L.) seeds subjected to osmotic stress induced by polyethylene glycol (PEG-6000). Three independent bioassays were conducted under controlled conditions. In the first assay, osmotic potentials ranging from 0 to −0.8 MPa were evaluated to characterize stress levels and identify conditions representative of moderate and severe water deficit. In the second assay, increasing doses (0 to 2.0 mL kg⁻¹ of seeds) of a commercial A. nodosum-based extract and its isolated mineral fraction were evaluated to determine the optimal application range. In the third assay, the selected treatment was evaluated under control conditions and under moderate (−0.6 MPa) and severe (−0.8 MPa) osmotic stress. Germination percentage, normal and abnormal seedlings, radicle and epicotyl length, and seedling vigor index were assessed. Osmotic stress progressively reduced germination and seedling growth, with the strongest effects observed at −0.6 and −0.8 MPa. Seed treatment with A. nodosum extract did not impair final germination but improved seedling development in a dose-dependent manner. The highest efficiency was observed at intermediate doses, with maximum normal seedling percentage predicted at 0.45 mL kg⁻¹ and maximum radicle growth at approximately 0.66 mL kg⁻¹. Under water deficit conditions, the complete extract promoted greater improvements in seedling performance than the mineral fraction, indicating that the beneficial effects were mainly associated with bioactive organic compounds rather than mineral nutrition alone. These findings provide new evidence that dose optimization is essential for maximizing the efficiency of seaweed-based biostimulants and demonstrate the potential of A. nodosum seed treatment as a sustainable strategy to improve maize establishment under water-limited conditions.

Lettuce (Lactuca sativa L.) is a widely consumed leafy vegetable cultivated globally, particularly under soilless systems to enable intensive and high-efficiency production. In these systems, precise nutrient solution management is essential, especially regarding calcium, an indispensable macronutrient involved in cell wall stabilization, membrane integrity, root development, and physiological responses to stress. This study evaluated the morphological and nutritional performance of crisp lettuce cultivars Mônica SF 31 and Veneranda grown using a nutrient film technique (NFT) system, using Calcário, Lithocal^®, and LT Supra^® as alternative calcium sources, alongside a control treatment. The experiment followed a randomized block design in a 4 × 2 factorial arrangement. Measured variables included root, leaf, and stem dry mass; stem length and diameter; and nutrient accumulation and gas exchange parameters. Data were subjected to analysis of variance and means were compared using Scott-knott test. Calcium supplementation significantly increased plant growth, with leaf fresh mass rising by 37% and root fresh mass by 56% compared to the control. Foliar calcium and magnesium concentrations were effectively enhanced by the treatments. Calcário, Lithocal^®, and LT Supra^® demonstrated effectiveness as calcium sources in soilless lettuce cultivation, promoting improved nutrient accumulation—particularly calcium and magnesium—and substantial gains in fresh biomass and root system development. Calcium supplementation is therefore recommended as a strategy to enhance productivity and crop quality in intensive soilless systems.

The success in the recovery of degraded areas is dependent on the acquisition of quality seedlings coupled. However, nursery activity is complex and involves significant operational and input costs. The present work had as its objective to evaluate the effects of the substrate and the chemical fertilization on the production and quality of Canavalia rosea (Sw.) DC. seedlings and their respective production costs. Ten treatments were tested, consisting of two substrates with sand: clay:coconut fiber (2:1:1 and 1:2:1) and five fertilizations (without fertilizer, with simple superphosphate, simple superphosphate + micronutrients, with NPK 04-14-08, and NPK 04-14-08 + micronutrients). The emergence speed index, emergence percentage, seedling height, stem diameter, leaf number, leaf area, shoot, root, and total dry mass, and Dickson quality index were evaluated. The 1:2:1 substrate and the fertilization levels with simple superphosphate, with simple superphosphate + micronutrients, with NPK 04-14-08, and with NPK 04-14-08 + micronutrients were higher than the control, with values 17% higher for seedling height, 5.4% for the number of leaves, and 18.9% for leaf area. Aiming at the low cost and the quality of the seedlings, it is recommended to use the substrate in the proportion 1:2:1, and fertilization with simple superphosphate.